Liquid injection cooling for compressor



Sept. 24, 1968 M. Y. WARNER I 4 LIQUID INJECTION COOLING FOR COMPRESSOR 5 Sheets-Sheet 1 Filed Oct. 20. 1966 &

' M.Y. WARNER IQUID INJECTION COOLING FOR COMPRESSOR Sept. 24, 1968 5 Sheets-Sheet 2 Filed Oct. 20, 1966 Sept. 24, 1968 M. Y. WARNER LIQUID INJECTION COQLING FOR COMPRESSOR 3 Sheets- Sheet 5 Filed Oct.

CL 7 W. "mg.-

United States Patent ABSTRACT OF THE DISCLOSURE A rotary compressor refrigeration apparatus provided with a flow passage for conducting liquid refrigerant from a condenser into the compression chamber of the compressor for cooling the compressor. The refrigerant is delivered from the condenser to the compressor at the discharge outlet in such a manner as to cause the compressed refrigerant passing outwardly through the outlet to aspirate the flow passage from the condenser to effectively preclude back flow of the compressed fluid through the passage to the condenser. The flow passage from the condenser is open to the compressor at the discharge outlet at substantially all times.

This invention relates to refrigeration apparatus and in particular to refrigeration apparatus utilizing a rotary compressor.

In one conventional form of refrigeration apparatus, liquid refrigerant is vaporized in an evaporator whereby a refrigeration effect is obtained as a result of the absorption of the heat of vaporization by the refrigerant fluid. The refrigerant vapor is then returned to a compressor wherein it is compressed and delivered to a condenser wherein it is cooled and resultingly liquefied for subsequent recirculation to the evaporator where it is again vaporized as discussed above. One form of compressor employed in such apparatus comprises a rotary compressor wherein a vaned rotor is rotated by a suitable electric motor in an offset relationship to a cylindrical compression chamber whereby the refrigerant vapor is drawn from the evaporator into a suction portion of the chamber for compression and, after compression, is delivered from a discharge portion of the chamber to the condenser. The compressor structure conventionally includes an integral electrical motor and is housed in a suitable sealed enclosure. In some refrigeration systems utilizing such rotary compressors, it has been found necessary to provide a precooler for removing super heat from the compressed vapor leaving the discharge portion of the compressor chamber to permit cooling of the electrical motor by the refrigerant vapor.

Compressors in such refrigeration systems may be damaged when operated at low suction pressures due to the fact that low suction pressures tend to raise the compressor temperature and where the suction pressures drop excessively the temperature may be increased above safe limits.

In one improved rotary compressor, the compressor parts are installed in the upper portion of the housing and the motor is installed in the lower portion so as to provide maximum reduction in noise by disposing the moving compressor parts above the level of the oil in a sump portion of the housing to avoid transmitting compressor vibrations to the housing through the oil. In such inverted rotary compressors, it has been found difficult to provide sufficient oil to the uppermost portion of the compressor parts by the conventional oiling systems.

The present invention comprehends a new and improved rotary compressor structure eliminating the above discussed disadvantages of the known rotary in a novel manner.

Thus, a principal feature of the present invention is the provision of a new and improved refrigeration apparatus.

Another feature of the invention is the provision of such a refrigeration apparatus having a new and improved rotary compressor structure.

A further feature of the invention is the provision of such a refrigeration apparatus having new and improved means for providing oil to the working parts of the rotary compressor.

Still another feature of the invention is the provision of such a refrigeration apparatus having new and improved means utilizing the relatively low suction pressure in the suction portion of the compression chamber for drawing oil to the working parts of the compressor structure.

Another feature of the invention is the provision of such a refrigeration apparatus having new and improved means for cooling the refrigerant vapor being compressed in the compression chamber.

A further feature of the invention is the provision of such a refrigeration apparatus having new and improved means for providing liquid refrigerant from the condenser to the compression chamber.

Still another feature of the invention is the provision of such a refrigeration apparatus having new and improved means for utilizing the variable pressures produced by the vaned rotor in compressing the refrigerant fluid to effect the desired injection of the liquid refrigerant from the condenser into the compression chamber.

Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein:

FIGURE 1 is a vertical section of a rotary compressor embodying the invention taken substantially along the line 11 of FIGURE 2 but including portions of the compressor housing;

FIGURE 2 is a horizontal section thereof taken substantially along the line 22 of FIGURE 1;

FIGURE 3 is a horizontal section thereof taken substantially along the line 3-3 of FIGURE. 1;

FIGURE 4 is a fragmentary vertical section taken substantially along the line 4-4 of FIGURE 3; and

FIGURE 5 is a schematic representation of the liquid refrigerant injection means embodying the invention.

In the exemplary embodiment of the invention as disclosed in the drawing, a rotary compressor generally designated 10 is shown to comprise a two-part housing 11 forming an enclosure for an electric motor 12 and a compressor structure 13. The housing 11 defines a lower sump space 14 for collection of lubricating oil 15 below the motor 12. As shown in FIGURE 1, the compressor structure 13 is disposed above the motor 12 for improved noise-free operation of the compressor. The compressor and motor assembly may be suspended within the housing 11 on springs as disclosed in the copending application of Claude Winkler, Ser. No. 449,968, filed Apr. 22, 1965, now Patent No. 3,300,125, issued Jan. 24, 1967.

As discussed briefly above, the invention comprehends .an improved compressor arrangement wherein the oil 15 is effectively delivered to the uppermost portion of the compressor structure for improved lubrication of the working parts thereof. More specifically, the invention comprehends such a compressor arrangement wherein suction pressure developed in the pump, or compression, chamber is utilized to draw the lubricating oil to the uppermost portion of the compressor structure.

Referring more specifically to FIGURES l, 2 .and 3, the compressor structure 13 includes a rear head 16,

a cylinder 17, and a front head 18 maintained in assembled relationship by suitable means such as bolts .19 and 20. Cylinder 17 defines a cylindrical compression chamber 21 in which a rotor 22 is disposed for offset rotation therein. Further, formed coaxially integrally with the rotor 22 are .an upward shaft extension 23 and a downward shaft extension 24. The rear head 16 is provided with an axial bore 25 in which the upper shaft extension 23 is journalled to form an upper bearing and the front head 18 is provided with an axial bore 26 in which the lower shaft extension 24 is journalled to form a lower bearing. Motor 12 includes a rotor 27 fixed to the shaft extension 24 and a stator 28 fixedly associated with the front head 18. Motor 12 rotates the rotor 22 and shaft extensions 23 and 24 about the longitudinal .axis thereof at a relatively high speed in operating the compressor 10. An axial bore 29 extends through shaft extension 24, rotor 22 and shaft extension 23 for delivering oil upwardly to the upper end 30 of the shaft extension 23 confronting a recess 31 in the upper surface of the rear head 16. A substantial pumping action is effected by the high speed rotation of the rotor and shaft extensions due to the centrifugal forces generated, but this pumping action has been found to be insufiicient to raise the oil fully to the upper end 30 of the shaft extension 23. To augment the centrifugal pumping action, compressor is arranged to utilize the suction pressure developed in chamber 21 to draw the oil upwardly to the upper end 30 of the shaft extension 23 and direct the drawn oil to the upper working or bearing surfaces of the compressor structure 13 for improved lubrication thereof.

More specifically, recess 31 is closed across the top thereof by a closure plate 32 secured to the rear head by means such as screws 33. A stepped bore 34 is provided in the rear head 16 extending downwardly from recess 31 to open through a lower surface 35 of the rear head overlying the compressor rotor 22 in the suction portion 36 of the compression chamber 21 as shown in FIG- URES 1 .and 3. As shown in FIGURE 1, the bore 34 may include an upper portion 37 and a reduced diameter lower portion 38 for channeling oil flow downwardly to the surface 35. The running clearance between rear head surface 35 and the upper surface 39 of the rotor 22 permits the suction pressure in chamber portion 36 to act through the bore 34, recess 31 and bore 29 in drawing the oil from the sump 14 but is small enough to provide a metering effect on the oil so that great quantities of oil will not enter the compression chamber. Liquid slugging which could damage the compressor is thereby prevented. The compressor 10 is of the high-side type, wherein compressed gas at above suction pressure is discharged into housing 11 and acts on the surface of oil to force it into the area of reduced pressure in bore 29. As shown in FIGURE 1, an oil pick-up tube 40 may be provided on the lower end of the lower shaft extension 24 to extend the lower end of the bore 29 to sump 14.

Shaft extension 24 may be provided with a plurality of radial ports 41 for flowing the lubricating oil outwardly to the lower bearing, and shaft extension 23 may be provided with a plurality of radial ports 42 for flowing the lubricating oil outwardly to the upper bearing thereby to provide lubrication thereof. In addition, the oil which lubricates the upper bearing flows downwardly to the face 39 of rotor 22 to provide lubrication for a pair of sliding vanes 54 and 55 (FIG. 3). These vanes and the walls of cylinder 21 also receive oil through bore 34, although a primary function of bore 34 is to permit the suction pressure to act at the upper end of shaft extension 23.

In the illustrated embodiment, the bore may have a diameter of .68 inch, the lower portion 43 of the bore 29 may have a diameter of inch, and the upper portion 44 of the bore 29 may have a diameter of .25 inch. The reduced portion 38 of the passage 34 may have a diameter of an inch.

Referring now to FIGURES l, 3, 4 and 5, compressor 10 further includes improved means for cooling the refrigerant vapor in the compression chamber 21 to permit elimination of external precooler apparatus and allow operation of the compressor 10 at low suction pressures without raising the temperature of the compressor above safe limits. The cooling of the refrigerant vapor in the compression chamber 21 is effected herein by delivering liquid refrigerant to the compression chamber from a condenser 45 of the refrigeration apparatus generally designated 46, as schematically illustrated in FIGURE 5. Thus, as shown in FIGURE 5, a portion of the liquid refrigerant in condenser 45 is returned to an outlet or discharge port 47 in the cylinder 17 provided for conducting the compressed refrigerant vapor to a muffler chamber 48. The compressed refrigerant vapor and the returned liquid refrigerant (vaporized in the cylinder by absorption of heat) is delivered from the mufiler chamber 48 through a passage 49 to the condenser wherein the compressed vapor is liquefied by the removal of heat therefrom in the conventional manner.

As shown in FIGURE 5, a conduit 50 is provided for conducting the liquid refrigerant to a conventional evaporator 51 wherein vaporization of the refrigerant liquid effects the desired heat absorption. The vaporized refrigerant is then conducted to an inlet port 52 in the cylinder 17 through a suitable return conduit 53 for recompression in chamber 21. As shown, the rotor 22 is provided with a pair of vanes or blades 54 and 55 which are slidably received in recesses 56 and 57 in the rotor to be urged outwardly therefrom against the cylindrical side wall 58 of the cylinder defining the chamber 21. The rotor is offset relative to the cylindrical chamber 21, and one portion 36 of the chamber 21 defines the suction portion of the chamber and a second portion 59 defines the discharge, or pressure, portion of the chamber with the discharge portion 59 being separated at all times from the suction portion 36 by one of the vanes 54 or 55.

The pressure in discharge portion 59 increases as a vane moves toward the outlet port 47, and varies between approximately suction pressure and a pressure in excess of condenser pressure. At times, the pressure of the refrigerant fluid in condenser 45 is therefore higher than the pressure in port 47 and a conventional check valve 60 is provided on the cylinder 17 in muffler chamber 48 for closing the port 47 at that time to permit only unidirectional flow of the refrigerant vapor outwardly from chamber 21 to condenser 45. When the pressure in port 47 is lower than the pressure in condenser 45, liquid refrigerant flows from the condenser 45 through the return conduit 61 to the port 47 and thence into the compression chamber 21 where it will vaporize and cool the refrigerant vapor being compressed therein.

More specifically, as shown in FIGURE 1, the conduit 61 extends through the housing .11 and is connected to a fitting 62 secured to the rear head in a threaded bore 63 at the outer end of a passage 64 opening into a downwardly opening recess 65. The threaded shank 66 of bolt 19 extends downwardly through a bore 67 in the upper end of recess 65, through recess 65 and through a coaxially aligned bore 68 in cylinder 17 into threaded association with a threaded bore 69 in the front head 18. The recess 65 and bore 68 are slightly larger than the outer diameter of the bolt shank 66 and, thus, define successive continuations of the flow path of the liquid refrigerant being returned from the condenser 45 through conduit 61.

A milled slot 70 is provided in the upper surface 71 of the front head 18 communicating with the bore 68 and with a through passage 72 in a fitting 73 in cylinder 17 opening upwardly into the lowermost port 47 of a series of vertically spaced outlet ports in the cylinder 17 including, in the illustrated example, ports 47a, 47b and 47c. As best seen in FIGURES l and 3, the passage 72 opens perpendicularly into the mid-portion 74 of the port 47. Thus, compressed refrigerant vapor flowing from chamber portion 59 through the port 47 tends to aspirate the passage 72 and prevent vapor flow through conduit 61 to the condenser 45 during delivery of the compressed vapor to the condenser. When, however, check valve 60 is closed as when the vapor pressure in chamber portion 59 is below the pressure in the condenser 45, liquid refrigerant may flow readily upwardly through the passage 72 and through the inlet 75 of the port 47 into the chamber portion 59.

As shown in FIGURE 4, the check valve 60* includes a plurality of fingers 76 separately closing the respective ports 47a, 47b and 470. The inlet of each of the respective ports is defined by an elongated slot 77 for facilitating the delivery of the compressed vapor as shown in FIGURE 4. As illustrated in FIGURE 5, the vanes ride on the side wall 58 of the cylinder outwardly of the slots 77.

Thus, the injection of the liquid refrigerant from condenser 45 into the chamber 21 is effected without the need for valve devices and the like in the return liquid refrigerant passage since the variable pressure in the discharge portion 59' of the compression chamber provides the desirable cyclical injection. The liquid injection means of the present invention provides a further highly desirable functioning in that it automatically compensates for low suction pressure conditions wherein the compressor tends to run hotter due to the decrease in the quantity of the heat absorbing refrigerant vapor delivered from the evaporator 51. When such low suction pressure conditions obtain in the chamber 21, more liquid refrigerant is withdrawn from the condenser 45 because of the greater pressure differential therebetween during the low pressure portion of the compression cycle. Thus, the rotary compressor is self-regulating as to the quantity of liquid refrigerant provided for cooling the vapor, thereby substantially improving the performance of the apparatus and permitting the elimination of external precooling devices while allowing the compressed vapor to pass directly into the space within the compressor housing 11 for separation of the oil 15 therefrom and cooling of the motor 12. The ability of this compressor to compensate for low suction pressures makes the compressor particularly useful in refrigeration systems of the capacity modulation type wherein capacity modulation is accomplished by throttling the suction line to the compressor. In this type of capacity modulation system, the load on the compressor is reduced as the suction pressure is reduced and as capacity is reduced. Since the load is reduced as capacity is reduced, economy of operation is realized as opposed to capacity modulation systems wherein refrigerant is by-passed around the evaporator but suction pressures remain constant.

The passage 72 may be of a preselected small size for effectively metering the liquid refrigerant to the chamber 21. As illustrated in FIGURE 1, the fitting 73 may project upwardly into the port 47 to provide a venturi means in constricting the portion adjacent the passage 72 for improved aspiration thereof during the flow of the compressed vapor through the port 47 into the mufiler chamber 48.

While I have shown and described one embodiment of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as defined in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a refrigeration system: compressor means defining a compression chamber and a discharge port for compressed refrigerant;

means in said chamber for compressing refrigerant fluid under cyclically varying pressure for flow outwardly through said discharge port;

condenser means connected to said discharge port for liquefying the compressed refrigerant fiuid flowed through said discharge port;

check valve means selectively closing said discharge port for permitting only unidirectional outward flow of the refrigerant fluid through said discharge port; and

means for cooling the compressor means comprising means forming a liquid refrigerant flow passage extending from said condenser means to a constantly open opening to said compression chamber at said discharge port upstream of said check valve means for transferring liquid refrigerant from said condenser means through said discharge port into said compression chamber when the pressure in said compression chamber decreases to less than the pressure in said condenser means and aspirating refrigerant from said flow passage when the pressure in said compression chamber becomes sufficient to cause flow of refrigerant fluid outwardly through said discharge port past said check valve means whereby back flow of refrigerant fluid through said flow passage to said condenser means is effectively precluded.

2. The refrigeration system of claim 1 wherein said compressor means includes a rotor mounted for offset rotation in said compression chamber and provided with sliding vanes effectively dividing said compression chamber into suction and discharge portions.

3. The refrigeration system of claim 1 wherein said liquid refrigerant flow passage means opens substantially perpendicularly into said discharge port.

4. The refrigeration system of claim 1 wherein said liquid refrigerant flow passage defines a metering orifice.

5. The refrigeration system of claim 1 wherein said liquid refrigerant flow passage opens into said discharge port.

6; The refrigeration system of claim 1 including a plurality of discharge ports each having an inlet portion communicating with said compression chamber and an outlet portion communicating with said condenser, said liquid refrigerant flow passage opening into only one of said discharge ports.

7. In a rotary compressor:

a housing defining an enclosure for receiving compressed gas;

a cylinder and front and rear heads defining a compression chamber wherein gas is compressed, said compression chamber having a suction portion, said front and rear heads each defining a bearing;

rotor means in said compression chamber for compressing gas and having lower and upper vertically extending shaft portions extending into said front and rear head bearings respectively, said rotor means forming a vertically extending first fluid flow passage communicating with said enclosure; and

means including said rear head forming a second fluid flow passage providing communication between said suction portion of said compression chamber and said vertically extending first fluid flow passage.

8. In a refrigeration system: compressor means defining a compression chamber and a discharge port for compressed refrigerant;

means in said chamber for compressing refrigerant fluid under cyclically varying pressure for flow outwardly through said discharge port;

condenser means connected to said discharge port for liquefying the compressed refrigerant fluid flowed through said discharge port;

check valve means selectively closing said discharge port for permitting only unidirectional outward flow of the refrigerant fluid through said discharge port; and

means for cooling the compressor means comprising means forming a liquid refrigerant flow passage be tween said condenser means and said discharge port upstream of said check valve means for transferring liquid refrigerant from said condenser means through said discharge port into said compression chamber when the pressure in said compression chamber decreases to less than the pressure in said condenser means, and said compressor means comprising a rotary compressor having a rear head, a cylinder having said discharge port therein, and a lfIOl'lt head, said rear head, cylinder, and front head cooperatively defining said compression chamber, and said liquid refrigerant flow passage means including a bolt hole extending from said rear head, through said cylinder and into said front head, a bolt extending through said bolt hole in said rear head and cylinder with clearance therebetween and threaded into said bolt hole in said front head, a passage in said rear head communicating with said bolt hole therein, a passage in said front head communicating with the bolt hole in the cylinder, and a passage in the cylinder communicating between said fluid flow passage and said passage in said front head.

9. The rotary compressor of claim 7 wherein said sec- 0nd fluid flow passage openly confronts said rotor means at said suction portion of said compression chamber.

10. The rotary compressor of claim 7 wherein said means defining said second fiuid flow passage includes means defining an upwardly opening recess in said rear head and a closure secured to said rear head for sealingly closing the upper portion of said recess.

11. The rotary compressor of claim 7 further including means defining a third fluid flow passage for providing communication between said first fluid flow passage and said rear head bearing.

References Cited UNITED STATES PATENTS 1,964,415 6/1934 Deventer -62-469 XR 3,105,633 10/1963 Dellario 62-505 XR 3,109,297 11/1963 Rinehart 62-505 XR 3,111,820 11/1963 Atchison 62--505 3,191,403 6/1965 Ladusaw 62-505 MEYER PERLIN, Primary Examiner. 

